Talk:Electromagnetic pulse/Archive 1

Archive 1

vehicles

How would an EMP effect ground cars or other vehicles?--64.79.177.254 (talk) 18:44, 15 July 2008 (UTC) It depends on the level of sophistication of the vehicle in question. The EMP could have no effect on older, pre-electronic processor, vehicles. On the newer vehicles, with hundreds of electronic components it could range from not being able to start/run to exploding the fuel tank. Actually, I have a nice video of a test we ran on a car in cooperation with the military channel's series "Future Weapons," unfortunately it is copy right protected.DerekFrankJames (talk) 12:12, 24 October 2008 (UTC)

Magnetic stripes

Does anyone know if an EMP would have an effect on magnetic stripe cards? - BlackWidower 00:32, 18 January 2006 (UTC)

I wouldn't be surprised. A lot in physics seems to have two sides to the coin. Just as a magnetic field can induce current in a wire, current passing through a wire generates a magnetic field. The MythBusters actually busted a relevant myth, but not for the same reasons.--Drat (Talk) 12:17, 23 January 2006 (UTC)

While I don't know if the actual cards would be effected by am EMP, the machines that read them would be, thus rendering the card useless anyway. Jen

The EMP from a high air burst is never strong enough at the Earth's surface to do this, see: [1]. The strongest EMP was produced by the Hardtack-Teak shot, not the Starfish test. (Teak was 3.8 Mt and was detonated at 77 km. EMP field strength (but not area coverage) is maximised for a burst at 40 km altitude, so Teak at 77 km would have produced a stronger ground level EMP than Starfish at 400 km.) The prompt EMP electric field from Teak was not measured due to instrument failure, but the late-time magnetic field variation was measured in a laboratory which studies solar storms:

"... the Apia Observatory at Samoa recorded the ‘sudden commencement’ of an intense magnetic disturbance – four times stronger than any recorded due to solar storms – followed by a visible aurora along the earth’s magnetic field lines (reference: A.L. Cullington, Nature, vol. 182, 1958, p. 1365)." - [2]

Since this EMP covered vast areas (though not as wide as those from Starfish), if the magnetic field was strong enough to wipe magnetic information off swipe cards, it would in 1962 have wiped magnetic audio and data tapes (a swipe card is just a plastic card with a strip of magnetic tape stuck on it). This didn't happen. If you think about it, the electromagnetic radiation which propagates is governed by Maxwell's equations (like visible light), and the magnetic field component of such a light velocity wave is given by:

$B=E/c$

Inserting the commonly used value for EMP of E = 50,000 volts/metre for the prompt field with a rise time of about 20 nanoseconds [3], the magnetic field strength is seen to be B = 0.000167 Teslas. This is only 2.9 times the natural magnetic field strength in Washington D.C. according to [4] which says the natural field there is 0.0000571 Testa. However, the ability to erase magnetic tape or credit card strip information depends on the field intensity in Orested not the field strength in Teslas:

"QUESTION: What is the danger that my tape will accidentally be erased?

"ANSWER: Standard open reel audio tapes have a coercivity of approximately 360 Oersteds. It takes an even greater magnetic field (approaching 900 Oersted) to completely erase a tape. For a comparison: The earth's magnetic field is 0.6 Oersted." [5]

EMP can't directly wipe out magnetic information. However, it could wipe magnetic information indirectly, if it induced a large current in a long conductor which runs near magnetic tape. Any conductor carrying an induced pulse of electric energy creates a magnetic field around it, which can easily be much stronger than the magnetic field of the EMP in free space. For example, a long overhead power transmission line, subjected to 50,000 v/m peak EMP will typically give a pulse with a peak of 1 million volts at 10,000 Amps. This will create tremendous magnetic fields. When these pulses go into transformers at the end of the power line, the transformer can explode or catch fire, but some of the energy is passed on before that happens, and can end up in home power systems. Any loop of cable connected to the mains will be a source of a powerful magnetic field which could wipe nearby magnetic tape, cards, and discs. 172.212.17.34 21:03, 30 March 2006 (UTC)

Why is this article titled Electromagnetic pulse?

Why is the title of the article Electromagnetic pulse when the article seems to be exclusively about EMP weapons? --hitssquad 06:26, 28 January 2006 (UTC)

Probably because the way that a powerful EMP has to be generated, in real-life, typically involves some sort of weapon, like a nuke. By the way, please sign your comments.--Drat (Talk) 06:32, 28 January 2006 (UTC)

I understand that Earth impactors may also create powerful Source Region EMP's within the 2-psi overpressure threshold, just like ground-level nuclear explosions do. L. Foschini. Electromagnetic interference from plasmas generated in meteoroid impacts. Europhysics Letters 43 (1998) 226. The article seems to me jump to the conclusion -- and to assume that everyone already knows -- that powerful EMP is exclusively a weapon effect. If it is indeed the case that powerful EMP's can only be created by weapons, perhaps the article should introduce that critical point before continuing to the rest of the article which is excusively about weapons. As it is it, looks as bizarre as would an article supposedly about cars that first introduces the topic of cars in a reasonable manner but then exclusively discusses Mercedes as if Mercedes are the only types of cars in existence -- or even possible -- and that everyone already knows this so well that it would be pointless to even mention the fact. --hitssquad 10:07, 5 February 2006 (UTC)

Then improve the article as you see fit. As it is, you know well more than I do on the subject, in terms of physics and all that.--Drat (Talk) 14:12, 5 February 2006 (UTC)

Another option may be to split this article in two, one named "Electromagnetic pulse (weapon)" and another one named "Electromagnetic pulse (telecommunications)", or something. -- Bovineone 08:06, 5 March 2006 (UTC)

Affected devices

I don't think that it's really made clear what devices are vulnerable -- as of right now the page says any unprotected electronic equipment but I'm sure there are things that are not vulnerable due to their small size and thus no 'antenna' to amplify the signal into the device. (By antenna, I mean anything that might serve to cause the device to absorb more EMP shock.) It might be worthwhile to note a few common electronics that would be vulnerable, such as cell phones -- speaking of which, are small personal electronic devices necessarily vulnerable? Home appliances most certainly are, as well as anything connected to the power grid due to the large EMP collecting abilities of the multitude of wiring. And -- are batteries necessarily vulnerable to EMP? I don't see how. I will do research later, if someone doesn't get to it first. - S. Komae (talk) 18:28, 29 March 2006 (UTC)

Microchips are vulnerable. In the 1950s and 1960s, America tested weapons at Nevada with yields up to 74 kilotons in air bursts and near surface bursts, which just produced 'clicks' on car radios. If you see B. J. Stralser's declassified 30 April 1961 EG&G report, Electromagnetic Effects from Nuclear Tests, you see that there is no damage to anything unless it was connected physically to a cable which had induced an EMP. Hence, in tower test, wth cables running from bomb to control point 50 km away, after serious damage in a 1951 test they had to switch off mains power and go over to diesel generators at shot time. In the 1958 Teak test the 3.8 Mt bomb exploded 77 km directly over Johnston Island, producing a massive EMP, but again no portable radios were destroyed. In the 1962 Starfish test, and also three Russian tests, lots of things were damaged but only if they were connected to long wires [6]. Portable radios working off batteries were OK. Although modern microchips are up to a million times more sensitive than valve/vacuum tube radios, the aerial size in a UHF cellular phone is really tiny compared to the long aerials of old HF valve/vacuum tube radios, so things balance out. I agree that anything you can fit in your pocket is not likely to be damaged by EMP, unless it is being recharged from the mains when the bomb exploded. (Batteries could only be damaged if they were being recharged at the time.) However, a safe, working cellular radio wouldn't be any use to you if the network (running from mains electricity) was zapped by EMP! 172.212.17.34 21:24, 30 March 2006 (UTC)

In the same vein, is it possible to build fuses or breakers that would protect devices plugged into the power grid? Also, are automobile electronics safe? BertW 05:53, 24 May 2006 (UTC)

Would an EMP cause damage to electronic equipment (with vulnerable components) which was switched off at the time of the attack? -- Milo —Preceding unsigned comment added by 81.171.2.42 (talk) 04:38, 23 February 2008 (UTC)

Specific effects of High Altitude EMP blast

For the purposes of a novel, I am wondering if anyone has a good guess about the effects if a large nuclear weapon or EMP weapon was detonated at GPS level, say 24,000 miles or so.

Basically wondering about the range of the effects. Would it affect all of the GPS satellites within the visible horizon? How about regular staellites that are at only 100 - 300 miles up?

Thanks!

4.178.238.32 18:25, 11 April 2006 (UTC)

The effective blastradius of the EMP field generated by a nuclear weapon, does not change when going into high altitude, if you know any specific data on the efectiveness of an EMP blast at ground level, it is safe to say that in space, or in high altitude, the effects would be the same. It is arguable that sattelites are built to withstand more galactic radiation then ground based electronic devices, maybe this has some shielding effect?

crashmatrix 23:05, 11 April 2006 (GMT+2)

Thanks for the reply. In reading today, however, several websites mentioned that High altitude blasts were visible from literally thousands of miles away, and I thought there was also an effect on blast radius with the lack of air resistance. What connection am I missing?

Thanks again!

4.178.45.132 03:24, 12 April 2006 (UTC)

Well, I'm not a 100% sure on this one, but the resistence in the atmosphere for EMP fields is non-existant or negligible, the fact that a high altitude blast is visible appearently implies that scientist (?) where 'listening' with sensitive equipment for EMP spikes, but at thousands of miles the impact is not great enough to affect normal equipment. A EMP field theoreticly extends into infinity, however the impact it makes deminishes over distance, so with equipment sensitive enough you could detect a EMP spike from the other way of the galaxy (if there where no background stellar radiation).

crashmatrix 00:49, 20 April 2006 (GMT+2)

High-altitude electromagnetic pulses (HEMP) produced by high-altitude bursts occur in an area of the atmosphere where the density of the air is low. Because of this, the gamma rays can travel very far before they are absorbed. These rays travel downward into the increasingly dense atmosphere. Here, they interact with the air to form ions as previously described. This region, called the deposition or source region, is roughly circular. It is thick in the middle and thinner toward the edges. It extends horizontally very far creating source regions that are over 1000 miles in diameter.(10) The size of it depends on the height of the burst and the yield of the weapon. The EMP in this source region gets deflected downward towards the earth due to the earth’s magnetic field. Although the fields produced from a high-altitude burst are not as great as those for a near-surface burst, they affect a much larger area.(11) Because of this huge potential, high-altitude bursts could be the most dangerous type of EMP. (http://www.geocities.com/capecanaveral/5971/emp.html) There hasn't been much experimentation with HEMPs in recent years so the effect on orbiting satelites is uncertain. --141.158.28.46 22:16, 25 April 2006 (UTC)

A graph showing the EMP as a function of bomb power, bomb design and burst altitude has just been added to the article, based on an unclassified 1975 computer simulation. 172.202.130.162 11:35, 7 May 2006 (UTC)

Trivia about uses in fiction

What is the purpose of this section, other than being an indiscriminate collection of facts? Is the fact that MacGyver can make an EMP generator or that "EMP" is the name of a magic spell in an N64 game supposed to help a reader understand what an electromagnetic pulse is? Why shouldn't this section be deleted? -- Centrx 22:27, 4 June 2006 (UTC)

I see your point. Dealt with the problem.--Drat (Talk) 07:40, 5 June 2006 (UTC)

I must say, even if this section was deemed trivia and not fit to stay in the main article, entirely deleting it without saving the list first by splitting it in its own article (which is now done with the Electromagnetic pulse in fiction article) was irrespectuous of the work done by the various contributors who had compiled this section, and borderline vandalism.

St Fan 13:30, 10 June 2006 (UTC)

Not if that article does not belong in an encyclopedia. It may very well be deleted for being an indiscriminate collection of information. -- Centrx 23:25, 12 June 2006 (UTC)

Shielding

The Boeing E-4 is apparently 'shielded' to be protected from EMP - how would this be done? Joffeloff 18:01, 12 July 2006 (UTC)

I would guess a faraday cage Rewt241

The plane could have negative pulse projectors but that would take massive amounts of energy since the pulse itself is powered through magnetism and shockwaves. Also, i would say that the shield could only work if it sense the pulse within a specific radius.—Preceding unsigned comment added by 69.158.71.24 (talk • contribs)

Rewt241 had it right. EMP protection mostly takes the form of Faraday cages - protective enclosures made of conductive materials that carry EM energy AROUND your electronics rather than THROUGH them. It's a tremendous hassle to design every single switch, button and knob to act as part of the cage, but it doesn't require anything exotic like "negative pulse projectors." I think one of this article's failings is that it gives the impression that EMP is a doomsday superweapon, when really both the effect and its countermeasures are the sort of thing you can teach in college engineering classes. —The preceding unsigned comment was added by 205.175.225.22 (talk) 16:40, August 23, 2007 (UTC)

Wouldn't an EMP have some effects?

Why does an article about electromagnetic pulse not discuss the effects of a scenario in which, somehow, electric equipment were in the radius of one? Would electric equipment be destroyed/damaged and would you then not be able to use it afterwards, or would the effects only be temporary, etc.? Kamikaze Highlander 03:57, 21 July 2006 (UTC)

Also, effects on animals and humans? AFAIK, electric impulses are used to transmit signals across the neurons in nervous system and whatever. So, I'd think EMP could at least disrupt those signals temporarily, if not outright damage the neurvous system or anything else (bioelectricity?). --Acolyte of Discord 22:11, 30 August 2006 (UTC)

I never really payed attention in physics, and haven't even really read most of the article, but I guess it would have something to do with the powerful magnetic field generating powerful electrical current in wires (basic physics), hence devices being damaged. Living things, of course, don't have wires. It'd be different if you were a cyborg, but for now that's mostly in the realms of fiction.--Drat (Talk) 09:30, 31 August 2006 (UTC)

Please look here[7] for some description of the effects of an EMP. As for the effects of EMP on humans etc? From the same site, "Electromagnetic weapons may be productively used against all elements in this model, and provide a particularly high payoff when applied against a highly industrialised and geographically concentrated opponent. Of particular importance in the context of strategic air attack, is that while electromagnetic weapons are lethal to electronics, they have little if any effect on humans. This is a characteristic which is not shared with established conventional and nuclear weapons." --Madbrood 15:28, 20 September 2006 (UTC)

Can someone add something about the effects to the article? I am really amazed that the article managed to be so long without offering even one example of something which might happen as a result of an EMP. For example, the 1985 tv film The Day After showed the cars and motorcycles were permanenetly disabled by the EMP of a nuclear blast occurred. I really thought that this article would tell whether that was fact or fiction, and if fact, offer an explanation of how it all works. But I came here to find nothing of that sort in the article, only here in the discussion. Can someone upgrade the article please? Thanks! --Keeves 00:48, 24 December 2006 (UTC)

I agree, I think the bulk of this article should be in an article called "Technical requirements for the use of an electromagnetic pulse as a weapon" which is probably not of sufficient interest to comprise the near entirety of the main article. Can someone rewrite? --70.247.192.110 19:30, 24 February 2007 (UTC)

Mad Explosions

I'm not a science-type fellow, but I'm assuming EMP waves don't cause mad explosions, fires, destruction, and such? (Any destruction might be the result of the trigger, but not the EMP?) JimmmyThePiep 04:10, 24 March 2007 (UTC)

That's science fiction/artistic licence for you.--Drat (Talk) 04:20, 24 March 2007 (UTC)

Defense

U.S. Army Source for EMP is the ARCIC Protection Division Protection Division Mission Statement

Add to the article how to defend or shield against EMP.—Preceding unsigned comment added by Frap (talk • contribs)

Only with reliable sources. No Sci-fi/made-up stuff.--Drat (Talk) 11:00, 26 March 2007 (UTC)

I wouldn't be surprised that if such information were put up it would be summarily removed by agents of the US Govt.. unless, of course, they knew it to be woefully inadequate ;) ... in any case, it's also not surprising that those with extensive knowledge on the subject seem to have completely refrained from posting. Though a little interesting. 71.61.184.208 04:50, 9 August 2007 (UTC)

Well, we can't just let any idiot come along and say "Why yes, I am an expert on electromagnetic warfare! You want proof?!? Refer to my first sentence!", can we. Part of the original reason the Original Research rule was brought in was to thwart physics cranks. The idea is to have published sources for your info.--Drat (Talk) 07:33, 9 August 2007 (UTC)

EMP protection doesn't require anything outlandish. It's just a matter of conductive shielding, thorough grounding, and careful filtering on all connections in & out. Just google "EMP shielding" and you'll find there are dozens of companies out there who build such equipment, though generally not for home use - all that filtering tends to mess up the high-speed signals we enjoy. (sorry for the lack of signature. I'm a wikinoob)—Preceding unsigned comment added by 205.175.225.22 (talk • contribs)

For more info, look up an unclassified standard called mil-std-188-125-1.—Preceding unsigned comment added by 12.206.247.59 (talk • contribs)

The EMP Commission and 2004 Report

Someone should mention the "Commission to assess the threat to the United States from electromagnetic pulse (EMP) attack", formed from the Floyd D. Spence National Defense Authorization Act for Fiscal Year 2001: [8] and the associated report: [9]. The commission was reestablished in 2006 from the National Defense Authorization Act for Fiscal Year 2006: [10] -- Mattbrundage 20:13, 3 May 2007 (UTC)

Power system failures as far away as Hawaii?

Is " power system failures as far away as Hawaii" an accurate description of fuses blowing and causing 300 series-connected streetlights (1-3% of the total) to go out?

http://arxiv.org/abs/physics/0307067 calls into question the oft-repeated 50 kV/m figure.

The external link to http://glasstone.blogspot.com/2006/03/emp-radiation-from-nuclear-space.html is largely a rebuttal to http://www.alternet.org/story/25738/ -- so shouldn't both or neither be referenced?

U.S. Army Source for EMP is the ARCIC Protection Division Proctection Division Mission Statement

--Guy Macon (talk) 11:09, 25 June 2007 (UTC)

EMP effects of a ground level nuke

I'm discussing this with a friend whose line of work comes into contact with first responders and homeland security, and we're debating what EMP effects there are, if any, from a ground level nuke.

I realize this probably seems like a silly question at first (if your city is nuked, who cares if your electronics are fried), but apparently the failure of radio communication on 9/11 (non-EMP-related) was a notable issue, crippling the ability of rescue teams to coordinate their efforts as the disaster was ongoing--so we're wondering, if a city is hit by a small nuke, will the on-site emergency responders be completely unable to communicate via radio in the immediate aftermath? (I know that cell towers will be physically gone, I'm talking about the survivability of electronics that aren't incinerated.)

This article does say that at ground level, free electrons are stopped quickly by air, but does that just mean "stopped quickly enough that nobody outside the city will be affected" or "stopped quickly enough that even inside the blast radius, assuming the blast itself didn't pulverize you, your handheld radios will still suffice to communicate over short distances"? (Sorry if I missed this information in the article somehow--I've really looked for it.) --24.90.146.245 22:10, 8 October 2007 (UTC)

This page is not set up to answer general questions about the topic - it's just here to discuss improvements to the article. That said, many radiation-related effects can do damge far beyond the blast radius of a nuclear bomb. See neutron bomb for example. Also, a nuclear bomb is not necessary in order to trigger an electromagnetic pulse, which can be made by a non-explosive device as well. So if you're looking for something to worry about then EMPs can remain on your list. ·:· Will Beback ·:· 21:35, 9 October 2007 (UTC)

The article's topic is general information regarding EMP effects, and a little information about the effects of EMP from a ground-level nuke would represent an improvement to the article. While the information is of personal interest, my question was intended to underline that the article is missing some fairly basic information (not esoteric or overly specific), of direct interest to people who seek out this page for coverage of EMP effects, and which was perhaps unintentionally overlooked by the article contributors. The information is relevant, notable, certainly in line with the rest of the information that's presented, and I'm not sure what might be a more appropriate wikipedia page for that information about EMP effects to be found. I'd hoped that this context was implied in my question. --24.90.146.245 07:02, 10 October 2007 (UTC)

I appreciate your point that the question may be shared by other readers and that the answer would provide useful information. However no single Wikipedia article contains a full coverage of any topic, nor does it need to. We're not here to advise government departments about how to prepare for electronic threats. The scenarios are infinite and the research is top secret. How much can one encyclopedia article really say? See also Electromagnetic bomb, High altitude nuclear explosion, Category:Electronic warfare, Category:Energy weapons, and Category:Electromagnetic radiation. If you can find additional sources that say more then let's add them. Otherwise we may be saying as much as we can. ·:· Will Beback ·:· 10:38, 10 October 2007 (UTC)

The radius depends on the size of the bomb or EMP charge and the altitude on which the EMP is triggered. I've seen a programme where they told that a nuclear bomb exploded on 48 kilometres the radius would be approx. Denver to Kansas, if it would explode on 480 km altitude, it would cover the entire area of the US, including a little of Canada and Mexico. An EMP also travels with the speed of light and no matter how small the nuke, electronics are totally fried, you don't have a little fried or something like that. Perhaps you have a better impression of what a threat an EMP is to your every day life. But chances are not that big I presume since you need to get an EMP still in place high above your target to have a devastating nationwide disaster. Mallerd 18:48, 10 October 2007 (UTC)

SOME electronics are fried. Some aren't. It depends on what they're made of, where they are, if they're plugged into the power grid or connected to anything else that can act as an antenna, and whether they're specifically designed to shrug off EMP. Like I said in another part of the page, EMP is not an unbeatable mysterious superweapon. Only a small portion of the information about it is classified (such as how its energy is distributed across different frequencies, since that info could be useful to someone who's trying to figure out how nuclear weapons work). See if a nearby university has an electrical engineering or physics professor who could explain how it all works, or at least point you towards a good textbook. 205.175.225.22 (talk) 20:54, 27 November 2007 (UTC)

More discussion about the Asteroid EMP blast effects

Basically what the title says. --Jack Zhang (talk) 09:05, 20 January 2008 (UTC)

Yes, asteroid is thrown into the article but without explanation of how this has the same effect as a nuclear explosion. Paulbrock (talk) 12:50, 6 April 2008 (UTC)

A discussion of EMP-proof practicle systems would be interesting

The Amish come to mind, hand run water pumps, blacksmithy, medical equipment, old furnaces with mechanical heat control (no electronics), direct mechanical energy systems (I'm conflicted here by http://www.gewp.org , all the etc. low tech stuff from ca. 1900 -> an entire laundry list of essential items that would withstand EMP. I am new to wiki Nukeh (talk) 19:58, 4 February 2008 (UTC)

Most devices aren't very vulnerable in and of themselves - their vulnerability comes from being connected to the power grid. The electric field from an EMP is talked about in terms of tens of thousands of volts per meter. For comparison, if you build up static electricity by rubbing your feet on the carpet and then zap someone, the electric field around your finger is about 3 MILLION volts per meter. So really, the field itself is not all that huge. Second, the waves are mostly low-frequency, long-wavelength waves. It takes a long conductor (at least several meters long) to act like an antenna and absorb the energy of a wave at those wavelengths. Most electrical devices just can't pick up such waves. Power lines, however, can - producing sudden spikes in voltage just like lightning does, with the same basic consequences of burning out plugged-in electronics.

So, in a nutshell, anything that's NOT directly connected to a long electrical conductor will be fine. Anything that IS directly connected to a long electrical conductor will experience a sudden voltage spike at the point of connection - which may or may not fry the circuits, depending on whether or not the thing has protection built in.

I wish I had a published source I could cite to put this info into the article with all the relevant numbers, but unfortunately I only have what's been handed down in-house from a coworker who specializes in protecting electronics from harmful signals. 205.175.225.22 (talk) 19:23, 10 April 2008 (UTC)

Just a thought...

...all the specific modern examples given are about a potential attack on the US. What about potential attacks on anywhere else... or, of course, attacks by the US? The science is the same, but once you get into things like "the high cost of real estate and traffic issues", it's not good enough to assume that what applies to the US applies to the rest of the world as well. 86.132.141.139 (talk) 00:17, 2 March 2008 (UTC)

...regarding the previous comment, you have to start somewhere. Maybe someone will add additional information that ties in other parts of the world more so than what has already been stated. Anyway, I was wondering about the potential for using EMPs against IEDs. —Preceding unsigned comment added by 70.15.43.23 (talk) 02:17, 2 April 2008 (UTC)

Do you mean a scaled-down device, tuned for the frequency range the IED could pick up best, fired directly at the IED like a gun? It's worth looking into, but I think most IED's are wired up so simply that any burst like that would just detonate them instead of disabling the electronics. If you were hoping to do the job just with a very strong electric field, your device would end up just arcing to the dirt instead of killing the electronics. 205.175.225.22 (talk) 19:30, 10 April 2008 (UTC)

Disturbing - Quality of Article

No offense, but this may be the least credible wiki page I have ever read. We are now allowing references to include blogs? This is a serious physics question, but there isn't a single peer reviewed scientific reference in the list. Is this (bad) public relations for wasteful DOD programs? Or merely entertaining science fiction? I'm not sure I can think of any other explanation for the content of this page. 67.128.143.3 (talk) 01:06, 9 December 2008 (UTC

I agree. I wanted to find out more about EMP and as normal I came to Wikipedia for my answer. But this article is one of the worst written article's I have ever seen on Wikipedia. It'd be better not to have anything! - xen 165.12.252.111 (talk) 05:04, 19 December 2008 (UTC)

I agree, but not that its the worst wiki article. If you skim through the other discussion, you will see dissatisfaction with the article has continued over the past few years. Comments include the fact that "those in the know" don't/won't publish here, too specific of focus on weapon EMP, too little focus on effects or remedy. Personally, I'd like a little less science and a little more primer before jumping into discussion about collisions. However, as has also been stated, if you don't like the article, then edit it! ...which I'll be setting about to do shortly. -- Parradoxx (talk) 20:36, 7 January 2009 (UTC)

This article, and the similar linked article on the Electromagnetic Bomb, have become a rather disorganized collection of facts with many important elements missing. I could write pages about what is wrong with these articles, but many of my comments about this are summarized on my page at http://www.futurescience.com/emp/emp-notes.html I would suggest beginning the re-organization and editing of these articles by separating Electromagnetic Pulse (nuclear) and Electromagnetic Pulse (non-nuclear) into separate articles. Nuclear EMP is unique in being a complex pulse that scientists usually separate into 3 distinct components. A brief description of the 3 components and their general effects should be near the beginning of the article. -- X5dna (talk) 18:57, 8 January 2009 (UTC)

I have added a section to the top of this article briefly describing the complex characteristics of nuclear EMP, which are commonly divided into E1, E2 and E3 pulses, according to their amplitude and time characteristics. I have also added a section about the reports of the United States EMP Commission. Those referenced reports, especially the 2008 Critical National Infrastructures Report, help to answer many of the questions posed much earlier on this discussion page about practical effects. It is impossible, though, to make definitive statements about the effects of nuclear EMP because of complex interactions of the detonation with the atmosphere, and especially with the earth's magnetic field. Also, the electrical and electronic infrastructure is constantly changing, as are the construction details of electronics equipment as our technology advances. X5dna (talk) 21:02, 11 January 2009 (UTC)

The Blog that is used as a Reference

There have been some comments about using the glasstone.blogspot.com site as a reference. In general, I agree that blogs should not be used as reference material, and eventually this will have to be corrected in this article. In this case, however, I understand why this site was used as a reference since it is basically a repository of references to scientific reports, along with quotations from those reports and enhanced illustrations from those reports.

Many of the original scientific reports on electromagnetic pulse are available now only as a PDF of an old photocopy of an important declassified government report, and many of the charts and diagrams (and even some of the text) are not as clearly legible as one would like.

Also, many important facts about electromagnetic pulse are not obvious from the information contained in a single source, but become clear from the aggregate of the information in two or three sources. I've read most of the reports referenced on that site, and many of them focus on very narrow aspects of the subject. Many of the comments on the glasstone.blogspot.com site put this compartmentalized information together in a very useful way. It is unfortunate that more comprehensive published references on this subject are not yet available.

With a few modifications, the particular referenced page from the glasstone.blogspot.com site would actually make a good review article on electromagnetic pulse that would be suitable for a peer-reviewed scientific publication. A comprehensive review article in a respected journal is overdue on this subject, but such an article has not been published since William Broad's series of articles in Science in 1981. X5dna (talk) 13:14, 16 January 2009 (UTC)

Improving the Quality of this Article

The first two paragraphs in the "Modern Scenarios" section seem very confusing to me, and seem to even contradict some other sections of the article. I think that it is trying to say that many media accounts about EMP are speculative (which is correct), but these existing paragraphs seem to be speculating about the speculations.

I think it would be better, and using more neutral language, if these two paragraphs were changed to read something like the following:

"Typical modern scenarios seen in news accounts speculate about the use of nuclear weapons by rogue states or terrorists in an EMP attack. Details of such scenarios are always controversial. It is impossible to know what kinds of capabilities that terrorists might acquire, especially if they are aided by state sponsors with advanced capabilities.

"Some rogue states have the missile capability to deliver a light payload to the necessary altitude for an EMP attack. Nuclear weapons, however, comprise a very heavy missile payload unless the weapons are quite advanced. Advanced weapons design enables larger weapon yields with lighter weight. It is difficult to know if any particular rogue state has the necessary combination of advanced missile technology and nuclear weapons technology to perform an effective nuclear EMP attack over an industrialized country."

I think that the above paragraphs are more factual and neutral than the existing paragraphs. Since this is the sort of statement, though, that can't be easily referenced to an authoritative source, I'm not going to change anything until other people have had ample opportunity to comment. X5dna (talk) 13:38, 16 January 2009 (UTC)

I've added an "Introduction and Early History" section to the article, with additional references. I don't think that this article has ever had a real introductory section. X5dna (talk) 13:28, 17 January 2009 (UTC)

I've consolidated the weapon yield information, which was formerly in two different areas, and was self-contradictory. The references that I added for this information are from the testimony given under oath by scientists at U.S. Congressional hearings. I've resisted using Congressional hearings in the past because I don't want this article to get politicized. However, in the case of some details regarding information about nuclear weapons, the statements of scientists given at these hearings is the best information available from a reliable public source. One always has to make sure that the information makes sense, though, on a level of the basic science involved. X5dna (talk) 09:35, 20 January 2009 (UTC)

I changed the Modern Scenarios section to wording that I believe is less speculative and less controversial. I included some of the changes that I suggested above on this page several days ago.X5dna (talk) 10:07, 20 January 2009 (UTC)

I've added a Common Misconceptions section to the end of this article. Although this section will probably be more controversial than the other things that I've added to this article, and it contains no references, I thought it was necessary after reading many other recent non-technical writings about this subject. In order to confirm that these misconceptions are common in popular writings about this subject, one only needs to spend a few minutes looking around the internet for examples, which are quite numerous. I think that it would be counterproductive to add links to popular misconceptions or to articles that promote confusion. X5dna (talk) 04:05, 23 January 2009 (UTC)

I added a short paragraph to the Weapon Yield section to make this section more accurate. The fast E1 component (that is damaging to computer and communications equipment) is proportional to the prompt gamma output of the weapon, but the solar-storm-like E3 component (that is so damaging to electric power grid transformers) is more closely proportional to the total energy yield. I think that this is one thing that makes nuclear EMP very confusing to most people, and it probably needs to be further clarified in this article. X5dna (talk) 14:26, 1 February 2009 (UTC)

I have re-written much of the "Weapon Distance" section for greater accuracy (and hopefully to make it more understandable for the average reader). For verification of the part that I re-wrote, I added a quotation from what is generally considered to be the most reliable reference textbook on the subject. I believe that the quotation also helps to clarify the subject. The quotation is not a copyright violation because the quote (from a respected textbook on nuclear weapons effects) is published by the United States federal government, and is therefore presumed to be in the public domain. X5dna (talk) 20:28, 4 March 2009 (UTC)

I added a mention of the U.S. EMP Commission's Critical National Infrastructures Report near the top of the article. From the earlier discussions on this page, that report about the likely EMP effects in 2008 is what many readers of this article are actually trying to find. X5dna (talk) 09:00, 6 March 2009 (UTC)

Recent Deletion

The just-added "Effects on Computers" section was deleted, and the reasons for deletion deserve some discussion. The added section was subjective and unreferenced speculation. (The many spelling errors in the deleted material will be ignored here.) The first paragraph began with "Under the circumstances that there is plenty of electricity in the air . . ." This is a meaningless statement from any basic scientific perspective. The writer may have been referring to something specific like static electricity or radio frequency energy, but this needed to be made clear.

The second sentence was also scientifically meaningless, referring to some sort of subjective feelings. The last sentence of the first paragraph began, "Rumor says that . . ." and continued with the statement of an unreferenced rumor. Wikipedia is most definitely not a place for spreading rumors in scientific articles. This is specifically in opposition to everything that Wikipedia is about. Unfounded rumors about the subject of this article are already widespread on the internet and elsewhere. This article should be a place where anyone who reads these rumors can go to find solid scientific information, not where they find additional rumors.

The last sentence of this section was accurate but unreferenced, and needed to be referenced to specific scientific articles, etc. Such studies have been done, but were not referenced here.

Finally, there is the question of whether the subject of specific EMP effects is even appropriate for this article. For as long as I have read this article, there has been a statement in the first paragraph referring the reader to another article for EMP effects. EMP can affect so many everyday items that they probably include most of the items that we now use everyday. A mere listing of these items would be extremely lengthy. It is likely that a new separate article should be created about EMP effects. Previous discussions here would indicate that specific effects on devices would not be appropriate for this article because the subject is so large -- and is subject to continuous change as our technology evolves. Also, since EMP effects depend upon the magnitude and nature of the EMP, you can get into a "how loud is noise?" type of question. Little electromagnetic pulses are occurring all the time, and are constantly inducing "noise spikes" on power lines and in electronic devices. Where do you draw the line between everyday electromagnetic pulses that cause small (but not immediately noticeable) levels of damage and larger pulses that begin to cause more immediate problems? X5dna (talk) 22:58, 13 March 2009 (UTC)

Problematic Sentence

I removed a sentence in the Practical Considerations section referring to web sites that offer information about protecting against EMP. There has historically been disagreement over the years about whether this sentence requires references, and the "citation needed" tag was just recently re-added to that sentence. References would be problematic for this statement -- since references could confirm the statement made in the article by referencing web sites with inaccurate or misleading information. I don't like the idea of using references that link to inaccurate or questionable information. Since the sentence in question seems to be of no significant degree of importance, I think the best solution (for now, at least) is just to delete it.

It is possible that, in the future, a more authoritative statement can be made that can be referenced with authoritative sources of information.

I also added a reference for the statements made earlier in the first paragraph of the Practical Considerations section. Statements in this section can be confirmed in the Science magazine report that was referenced earlier in this article. X5dna (talk) 13:56, 25 March 2009 (UTC)

Failure rates of affected devices

The article does not seem to address the percentage or severity of devices that would be affected by an EMP. There appears to be a popular notion that an EMP will destroy all technology within a certain radius. For example, I recall a scene in the movie "The Day After" in which all of the "newer" cars on a highway immediately stop, purportedly due to EMP damage to the engine computers. Although I am not disputing that *some* cars are going to be affected, would it really affect 100% of the cars? Would the damage always cause engine failure, instead of some other result? As an electrical engineer (although admittedly not an expert in EMPs), I am skeptical of many of these claims.

The authors of the current article cite some of the systems affected during nuclear weapons testing, but what is not mentioned is the number and kinds of systems that were *not* affected. For example, it cites that during the Starfish Prime test, 300 streetlights went out in Hawaii, 800 miles from the test. Although that sounds impressive, there were probably many more streetlights that were not affected and probably many other electrical systems that continued to function normally.

Consider two other forms of electrical transients, each of which has been researched more extensively than EMPs: lightning strikes and electrostatic discharge. Both of these transients cause significant damage to electrical systems, but neither causes 100% failure. Lightning can travel up to 10 miles from cloud to ground; however, this should not be interpreted to mean that lightning will affect every piece of equipment in a 10 mile radius. Similarly, even though an EMP has been shown to affect equipment hundreds of miles away, this cannot be interpreted to mean that every piece of equipment within that radius will be affected. The former is a statement of what *can* happen (i.e. what has been observed to be possible), not what *will* happen (i.e. the likely outcome).

Even when a piece of equipment is affected by lightning or ESD, total immediate failure of the device is not the only outcome. In some cases, the device may fail immediately after exposure to the transient, but then work properly when rebooted. Another possibility is that part of the device malfunctions and is unusable, but the rest of the device is unaffected. Sometimes the device might appear to work properly, but then malfunction when a particular state or set of inputs is reached, resulting in intermittent malfunctions or failures. The transient can also shorten the lifetime of components in the device, even if the device works properly during that lifetime. Finally, sometimes the transient has no measurable effect.

Lightning strikes demonstrate a distribution of the percentage and severity of affected devices. The closer one is to a lightning strike, the more likely a device is going to be affected, and it is more likely to be severely affected. The fact that the millions of lightning strikes which happen every day have not wiped out all electronics demonstrates that neither of these probabilities are 100%. There are other factors which make a precise prediction difficult (e.g., the energy of the strike, altitude, geography, and distribution of nearby equipment). The transient often takes the "path of least resistance," reducing the impact on other devices. I would expect many of these factors to also affect the damage caused by an EMP. There probably would be a region near the explosion where most devices would fail. As one moved further away from the epicenter, fewer devices would be affected and the severity of the effect would be less.

In conclusion, I find it hard to believe that an EMP would bring most of North America back to the stone age. It is one thing to report what has been observed to be possible, but that doesn't mean that every device is going to be affected that way. The article could thus use a discussion of failure rates. 71.86.204.74 (talk) 02:46, 29 March 2009 (UTC)

Although I agree with much of what was written just above, I think that the level of uncertainty about the damage that a nuclear EMP attack would do is a good reason not to make any concrete statements about the subject in this article. I wrote most of the Introduction and the Popular Misconceptions sections of this article, and that's why I was careful to state that Starfish Prime only knocked out 1 to 3 percent of the streetlights in Hawaii. It is also why I referred the reader to the 200-page "National Critical Infrastructures Report" for an assessment of likely damages.

Because the potential EMP damage situation is so terribly complex, any brief analysis of likely damages in 2009 is always going to be misleading. If there is a concise way to describe the huge complexity of the potential damage situation, then I think that such a description would be welcomed. Because the potential damage situation is so complex, I don't know how that would be done.

I think that it is inaccurate to compare the EMP situation with lightning and other everyday transients, though. There are huge numbers of lightning suppressors scattered throughout the power grid. In some parts of the country, you can see them on just about every utility pole. Most people also have surge suppressors appropriate for common voltage transients in their homes. Power supplies in computers and other sensitive electronics equipment also have a certain amount of transient suppression of a type that is appropriate for lightning.

EMP suppressors, however, are almost totally absent, and the E1 component of EMP is too fast for ordinary lightning suppressors. If EMP suppressors were as widely used as ordinary lightning suppressors, then the potential of EMP causing a serious problem would be quite dramatically reduced. EMP protection is not terribly difficult, nor is it particularly more expensive than lightning suppression, it is just not used.

Although this is just conjecture on my part, as someone who has spent the last 30 years dealing with lightning induced damage, I think that if the amount of lightning suppression were reduced to the current level of EMP protection, the result would be that damage levels to electronics by lightning would go up by a factor of at least a thousand, and that lightning damage soon would become one of our major economic and social problems.

There is also a problem with the statement that "as one moved farther away from the epicenter, fewer devices would be affected." Although that is true to a limited extent, especially for a small weapon, it is important to remember that the EMP is not generated directly from the detonation. Gamma rays from the explosion hitting the upper atmosphere cause the EMP to be generated a few miles right over your head, even if the detonation is a thousand miles away. This is not in any way comparable to lightning.

It would certainly be wrong to state in this article that an EMP would take most of North America back to the stone age, but it would also be wrong to state that it would not. It is always possible that the combination of a widespread strong E1 pulse, followed immediately by an long E3 pulse that generates DC-like currents that can severely upset the power grid, could cause an unpredictable and catastrophic series of cascading infrastructure failures. X5dna (talk) 07:05, 30 March 2009 (UTC)

What actually is an EMP though?

I've been studying physics at university for nearly 4 years now and it occurred to be that I still don't really understand what an EMP is. I came to Wikipedia hoping for an answer but the article breezes over the fundamental physical mechanism of an EMP. What I can't quite grasp is how a "fluctuation" in both an electric and magnetic field is able to propagate over large distances. My intuition tells me that when you've got a fluctuating electric and magnetic field then the fields interact and all the energy gets dumped into electromagnetic waves (i.e. photons). If you ignore that though and just consider the magnetic and electric fields separately, it still doesn't make sense to me how the energy is transferred. Even in a vacuum, a field originating from a single point drops off as 1/distance but I'm not sure if the same would apply for "fluctuations" in the field. Anyway, if anyone knows a mathematical description of the physics involved (e.g. how the Maxwell equations are used to show the production of an EMP) I think that would be a great benefit to the article. Waofy (talk) 17:08, 14 May 2009 (UTC

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Much of the problem is that there are three different electromagnetic pulses that are generated from a high-altitude nuclear explosion, each with a somewhat different generation mechanism. A complete mathematical explanation of the mechanisms involved in all three would make the article very long and too technical for the average reader. I do think, however, that an additional brief description of the generation of the E1 component probably needs to be added in the Characteristics of Nuclear EMP section, although there is a description later in the article in the quotation from the Federation of American Scientists.

The E3 generation mechanism is much simpler since the large movement of the Earth's magnetic field simply puts the entire affected area inside of a changing magnetic field, which induces currents in any very long electrical conductor.

A more complete mathematical description of the process of the E1 component generation can be found in the SUMMA Foundation Theoretical Notes at http://www.ece.unm.edu/summa/notes/Theoretical.html, in particular Theoretical Notes TN368 and TN363 at that site. X5dna (talk) 21:06, 15 May 2009 (UTC)

There are basically two reasons that the EMP field strength does not drop off at the commonly expected 1/distance rate. The major reason is that the upper atmosphere quickly becomes fully ionized, and therefore electrically conductive at a certain point. An electric field cannot be effectively generated within an electrical conductor. So although the ionized atmosphere is not a perfect conductor, for any particular nuclear explosion (or other event that generates gamma radiation), there is a saturation effect that limits the maximum field strength that can be generated. Without this saturation effect, the EMP field strength could be quite considerably higher in the area around the detonation point.

Secondly, the Earth's magnetic field contributes to the generated electromagnetic field. The Earth's magnetic field does not exist solely at the point where the gamma radiation is generated (and it is irrelevant at that point, anyway); but is spread fairly evenly over the entire affected area. The Earth's magnetic field only makes its critical contribution to the generation of the EMP field in the region where the gamma radiation hits the electrons in the atoms of the upper atmosphere, and this is in a region that is much closer the the ground observer than the detonation point is. X5dna (talk) 01:20, 16 May 2009 (UTC)